(1) Field of the Invention
The present invention relates to a Consumer Electronics Control (CEC) communications device executing communications control on the CEC which represents a device control signal and a control protocol defined by the High-Definition Multimedia Interface (HDMI) standard, and an audio and visual device using the CEC communications device.
(2) Description of the Related Art
Recently, the serial communication has been commonly used to operate one device via another device. As an example, the HDMI standard has additionally defined the CEC utilized for mutual control of audio and visual devices, such as a television receiver (TV), a Digital Versatile Disc (DVD) player, and a DVD/Hard Disk Drive (HDD) recorder. The CEC employs single-line bidirectional asynchronous serial communication. Since a CEC line is directly connected to all of the appliances in a network, a malfunction of one appliance is detrimental to the entire network.
Suppose a CEC output terminal of an appliance is fixed to the low level due to a software malfunction. This causes all the communications lines on the entire network to be fixed to the low-level, resulting in a communication breakdown in the entire CEC network.
When detecting a communication malfunction, a typical serial communication involves conducting a communication test while physically disconnecting all of output terminals of the local appliance one by one to recover from the failure (Patent Reference 1: Japanese Unexamined Patent Application Publication No. 08-87458). However, the CEC standard provides no communication recovery capability in the case where a communication malfunction is detected.
It is rather unfortunate that the CEC currently has no counter measure when a communication breakdown occurs due to the software malfunction and the resulting fix of the CEC output terminal to the low level. Thus, the CEC network is left disabled. A possible solution to the problem also faces another challenge: before the CEC network is recovered, the HDMI cables should be re-connected and the CEC reset.
Under present circumstances, there are not many CEC-compliant appliances, which does not cause so much trouble for resetting the CEC by re-connecting the HDMI cables. However, the troubles below can break out in the future.
Each manufacturer of home appliances is promoting a project to encourage CEC-compliant co-operations between home appliances, leading to further introductions of a variety of CEC-compliant appliances to the market. Concurrently, an increase in such appliances will cause more CEC-misbehaving appliances, followed by more CEC-related communication malfunctions. This is very troublesome since every CEC-related communication malfunction requires the HDMI cables of all the appliances on the network to be re-connected.
The present invention is conceived in view of the above problems and has as an object to provide a CEC communications device and an audio and visual device, the CEC communications device which eliminates a troublesome process to solve the CEC-related communication malfunction when the CEC communications device detects a CEC-related communication malfunction caused by a software malfunction and improves serviceability of the CEC communications by automatically resetting the CEC to execute a CEC communication recovery.